IMS Health Holdings Inc. is in the final stages of preparing to launch an initial public stock offering that could value the prescription-data provider at $7 billion, said people familiar with the matter.

IMS, owned by private-equity firms TPG, Leonard Green & Partners LP and the Canada Pension Plan Investment Board, will soon start a road show to pitch investors on its shares, which are expected to begin trading within the next two weeks. The private-equity firms are aiming to raise around $1 billion in the sale, the...